The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely
enclosed by land: on the north by Anatolia and Europe, on the south by Africa, and on the east by the Levant. The sea is
technically a part of the Atlantic Ocean, although it is usually
identified as a completely separate body of water.

The name Mediterranean is derived from the Latinmediterraneus, meaning "inland" or
"in the middle of the earth" (from medius, "middle" and
terra, "earth"). It covers an approximate area of 2.5
million km² (965,000 sq mi), but its
connection to the Atlantic (the Strait of Gibraltar) is only
14 km (9 mi) wide. In oceanography, it is sometimes called the
Eurafrican Mediterranean Sea or the European
Mediterranean Sea to distinguish it from mediterranean seas
elsewhere.[1][2]

The Mediterranean Sea has an average depth of 1,500 metres
(4,920 ft) and the deepest recorded point is 5,267 metres (about
3.27 miles) in the Calypso Deep in the Ionian Sea.

Name

The term Mediterranean derives from the Latin word mediterraneus,
meaning "in the middle of earth" (medius, "middle" +
terra, "land, earth"). This is either due to the sea being
surrounded by land (especially compared to the Atlantic Ocean) or
that it was at the centre of the known world. The Greek name is
Mesogeios (Μεσόγειος), "inland, interior" (from μέσο,
"middle" + γη, "land, earth")[4].

The Mediterranean Sea has been known by a number of alternative
names throughout human history. For example the Romans commonly
called it Mare
Nostrum (Latin, "Our Sea"). Occasionally it was known as
Mare Internum by (Sallust, Jug. 17).

Biblically, it has been
called the "Hinder Sea", due to its location on the west coast of
the Holy Land, and
therefore behind a person facing the east, as referenced in the Old Testament, and
sometimes translated as "Western Sea", (Deut. 11:24; Joel 2:20), and also
the "Sea of the Philistines" (Exod. 23:31), due to the peoples
occupying a large portion of its shores near the Israelites. However,
primarily it was known as the "Great Sea" (Num. 34:6,7; Josh. 1:4, 9:1,
15:47; Ezek.
47:10,15,20), or simply "The Sea" (1 Kings 5:9; comp.1 Macc.
14:34, 15:11).

In Modern
Hebrew, it has been called Hayam Hatikhon (הַיָּם
הַתִּיכוֹן), "the middle sea", a literal adaptation of the German
equivalent Mittelmeer. In Turkish, it is known as
Akdeniz, "the white sea". In modern Arabic, it is known as
al-Baḥr al-Abyaḍ al-Mutawassiṭ
(البحر الأبيض المتوسط), "the White Middle Sea." And, lastly, in
Islamic and older Arabic literature, it was referenced as Baḥr al-Rūm (بحر الروم), or "the
Roman/Byzantine Sea."

History

As a sea around which some of the most ancient human
civilizations were arranged, it has had a major influence on the
history and ways of life of these cultures. It provided a way of
trade, colonization and war, and was the basis of life (via fishing
and the gathering of other seafood) for numerous communities
throughout the ages.

The combination of similarly-shared climate, geology and access
to a common sea has led to numerous historical and cultural
connections between the ancient and modern societies around the
Mediterranean.

On the Northeast. The West Coast of Italy. In the Strait of
Messina a line joining the North extreme of Cape Paci (15°42'E)
with Cape Peloro, the East extreme of the Island of Sicily. The North Coast of
Sicily.

Oceanography

Predominant currents for June.

Being nearly landlocked affects the Mediterranean Sea's
properties; for instance, tides
are very limited as a result of the narrow connection with the
Atlantic Ocean. The
Mediterranean is characterized and immediately recognized by its
deep blue color.

Evaporation
greatly exceeds precipitation and river
runoff in the Mediterranean, a fact that is central to the water
circulation within the basin.[6]
Evaporation is especially high in its eastern half, causing the
water level to decrease and salinity to increase eastward.[7] This pressure
gradient pushes relatively cool, low-salinity water from the
Atlantic across the basin; it warms and becomes saltier as it
travels east, then sinks in the region of the Levant and circulates westward, to spill over
the Strait of Gibraltar.[8] Thus,
seawater flow is eastward in the Strait's surface waters, and
westward below; once in the Atlantic, this chemically distinct
"Mediterranean Intermediate Water" can persist thousands of
kilometers away from its source.[9]

Bordering
countries

Map of the Mediterranean Sea.

Twenty-two modern states have a coastline on the Mediterranean
Sea. They are:

The Mediterranean Sea has an average depth of 1,500 metres
(4,920 ft) and the deepest recorded point is 5,267 meters
(about 3.27 miles) in the Calypso Deep in the Ionian Sea. The coastline extends for
46,000 kilometres (28,600 mi). A shallow submarine ridge
(the Strait of
Sicily) between the island of Sicily and the coast of Tunisia divides the sea in two main subregions
(which in turn are divided into subdivisions), the Western
Mediterranean and the Eastern Mediterranean. The
Western Mediterranean covers an area of about 0.85 million km²
(0.33 million sq mi) and the Eastern
Mediterranean about 1.65 million km² (0.64
million sq mi).

Tectonic
evolution

The geodynamic
evolution of the Mediterranean Sea was provided by the convergence
of European and African plates. This process was driven by the
differential spreading along the Atlantic ridge, which led to the
closure of the Tethys
Ocean and eventually to the Alpine orogenesis. However, the
Mediterranean also hosts wide extensional basins and
migrating tectonic arcs, in response to its
land-locked configuration.

According to a report published by Nature in 2009, scientists think that
the Mediterranean Sea was mostly filled during a time period of
less than two years, in a major flood (the Zanclean
flood) that happened approximately 5.33 million years ago,
in which water poured in from the Atlantic Ocean and through the Strait of
Gibraltar, at a rate three times the current flow of the Amazon River.[11]

Eastern
Mediterranean

In middle Miocene times,
the collision between the Arabian microplate and Eurasia led to the separation between the
Tethys and the Indian oceans. This
process resulted in profound changes in the oceanic circulation
patterns, which shifted global climates towards colder conditions.
The Hellenic Arc, which has a land-locked configuration, underwent
a widespread extension for the last 20 Myr due to a slab roll-back
process. In addition, the Hellenic Arc experienced a rapid rotation
phase during the Pleistocene, with a counterclockwise
component in its eastern portion and a clockwise trend in the
western segment.

Central
Mediterranean

The opening of small oceanic basins of the central Mediterranean
follows a trench migration and back-arc opening process that
occurred during the last 30 Myr. This phase was characterized by
the counterclockwise rotation of the Corsica-Sardinia block, which
lasted until the Langhian (ca.16 Ma), and was in turn followed by a
slab detachment along the northern African margin. Subsequently, a
shift of this active extentional deformation led to the opening of
the Tyrrenian basin.

Western
Mediterranean

Since Mesozoic to Tertiary times, during
convergence between Africa and Iberia, the Betic-Rif mountain belts
developed. Tectonic models for its evolution include: rapid motion
of Alboranmicroplate, subduction zone and
radial extensional collapse caused by convective removal of
lithospheric mantle. The development of these intramontane Betic
and Rif basins led to the onset of two marine gateways which were
progressively closed during the late Miocene by an interplay of
tectonic and glacio-eustatic processes.

Paleoenvironmental
analysis

Its semi-enclosed configuration makes the oceanic gateways
critical in controlling circulation and environmental evolution in
the Mediterranean Sea. Water
circulation patterns are driven by a number of interactive factors,
such as climate and bathymetry, which can lead to precipitation of
evaporites. During late Miocene times, a
so-called "Messinian
Salinity Crisis" (MSC hereafter) occurred, which was triggered
by the closure of the Atlantic gateway. Evaporites accumulated in the Red Sea Basin (late Miocene), in the Carpatian
foredeep (middle Miocene) and in the whole Mediterranean area (Messinian). An accurate age
estimate of the MSC—5.96 Ma—has recently been astronomically
achieved; furthermore, this event seems to have occurred
synchronously. The beginning of the MSC is supposed to have been of
tectonic origin; however, an astronomical control (eccentricity)
might also have been involved. In the Mediterranean basin, diatomites are regularly found underneath
the evaporite deposits,
thus suggesting (albeit not clearly so far) a connection between
their geneses.

The present-day Atlantic gateway, i.e. the Strait of
Gibraltar, finds its origin in the early Pliocene. However, two
other connections between the Atlantic Ocean and the Mediterranean
Sea existed in the past: the Betic Corridor
(southern Spain) and the Rifian
Corridor (northern Morocco).
The former closed during Tortonian times, thus providing a "Tortonian
Salinity Crisis" well before the MSC; the latter closed about 6 Ma,
allowing exchanges in the mammal fauna between Africa and Europe. Nowadays, evaporation is more relevant
than the water yield supplied by riverine water and precipitation,
so that salinity in the Mediterranean is higher than in the
Atlantic. These conditions result in the outflow of warm saline
Mediterranean deep water across Gibraltar, which is in turn
counterbalanced by an inflow of a less saline surface current of
cold oceanic water.

The Mediterranean was once thought to be the remnant of the Tethys Ocean. It is
now known to be a structurally younger ocean basin known as Neotethys. The Neotethys formed during the
Late Triassic and Early Jurassicrifting of the African and Eurasian plates.

Paleoclimate

Because of its latitudinal position and its land-locked
configuration, the Mediterranean is especially sensitive to
astronomically induced climatic variations, which are well
documented in its sedimentary record. Since the Mediterranean is
involved in the deposition of eolian dust from the Sahara during dry periods,
whereas riverine detrital input prevails during wet ones, the
Mediterranean marine sapropel-bearing sequences provide
high-resolution climatic information. These data have been employed
in reconstructing astronomically calibrated time scales for the
last 9 Ma of the Earth's history, helping to constrain the time of
past Geomagnetic Reversals[12].
Furthermore, the exceptional accuracy of these paleoclimatic
records have improved our knowledge of the Earth's orbital
variations in the past.

Ecology and
biota

As a result of the drying of the sea during the Messinian Salinity Crisis,[13] the
marine biota of the Mediterranean are derived primarily from the Atlantic Ocean.
The North Atlantic is considerably colder and more nutrient-rich
than the Mediterranean, and the marine life of the Mediterranean
has had to adapt to its differing conditions in the five million
years since the basin was reflooded.

The Alboran Sea
is a transition zone between the two seas, containing a mix of
Mediterranean and Atlantic species. The Alboran Sea has the largest
population of Bottlenose
Dolphins in the western Mediterranean, is home to the last
population of harbour porpoises in the Mediterranean, and
is the most important feeding grounds for Loggerhead Sea Turtles in Europe.
The Alboran sea also hosts important commercial fisheries,
including sardines and swordfish. In 2003, the World Wildlife Fund raised concerns about
the widespread drift net fishing endangering populations
of dolphins, turtles, and other marine animals.

Environmental threats

Biodiversity

Invasive
species

The opening of the Suez
Canal in 1869 created the first salt-water passage between the
Mediterranean and Red Sea.
The Red Sea is higher than the Eastern Mediterranean, so the
canal serves as a tidal strait
that pours Red Sea water into the Mediterranean. The Bitter Lakes, which are hyper-saline
natural lakes that form part of the canal, blocked the migration of
Red Sea species into the Mediterranean for many decades, but as the
salinity of the lakes gradually equalized with that of the Red Sea,
the barrier to migration was removed, and plants and animals from
the Red Sea have begun to colonize the Eastern
Mediterranean. The Red Sea is generally saltier and more
nutrient-poor than the Atlantic, so the Red Sea species have
advantages over Atlantic species in the salty and nutrient-poor Eastern
Mediterranean. Accordingly, Red Sea species invade the
Mediterranean biota, and not vice versa; this phenomenon is known
as the Lessepsian migration (after Ferdinand
de Lesseps, the French engineer) or Erythrean invasion. The construction of the
Aswan High Dam across the Nile
River in the 1960s reduced the inflow of freshwater and
nutrient-rich silt from the Nile
into the Eastern Mediterranean, making conditions there even more
like the Red Sea and worsening the impact of the invasive
species.

Invasive
species have become a major component of the Mediterranean
ecosystem and have serious impacts on the Mediterranean ecology,
endangering many local and endemic Mediterranean species. A first look at
some groups of exotic species show that more than 70% of the
non-indigenous decapods and about 63% of the exotic fishes
occurring in the Mediterranean are of Indo Pacific origin,[14]introduced into the
Mediterranean through the Suez Canal. This makes the Canal as the
first pathway of arrival of “alien” species into the
Mediterranean. The impacts of some lessepsian species have proven
to be considerable mainly in the Levantine basin of the
Mediterranean, where they are replacing native species and becoming
a “familiar sight”.

According to the International
Union for Conservation of Nature definition, as well as Convention on Biological
Diversity(CBD) and Ramsar Convention terminologies, they
are alien species, as they are non native (non-indigenous) to the
Mediterranean Sea, and they are outside their normal area of
distribution which is the Indo-Pacific region. When these species
succeed in establishing populations in the Mediterranean sea,
compete with and begin to replace native species they are “Alien
Invasive Species”, as they are an agent of change and a threat to
the native biodiversity. Depending on their impact, Lessepsian
migrants are either alien or alien invasive species. In the context
of CBD, “introduction" refers to the movement by human agency,
indirect or direct, of an alien species outside of its natural
range (past or present). The Suez Canal, being a artificial (man
made) canal, is a human agency. Lessepsian migrants are therefore
“introduced” species (indirect, and unintentional). Whatever
wording is chosen, they represent a threat to the native
Mediterranean biodiversity, because they are non-indigenous to this
sea. In recent years, the Egyptian government's announcement of its
intentions to deepen and widen the canal have raised concerns from
marine biologists, fearing that such an act
will only worsen the invasion of Red Sea species into the
Mediterranean, facilitating the crossing of the canal for yet
additional species.[15]

Arrival of new
tropical Atlantic species

In recent decades, the arrival of exotic species from the
tropical Atlantic has become a noticeable feature. Whether this
reflects an expansion of the natural area of these species that now
enter the Mediterranean through the Gibraltar straight, because of
a warming trend of the water caused by Global Warming; or
an extension of the maritime traffic; or is simply the result of a
more intense scientific investigation, is still an open question.
While not as intense as the “lessepsian” movement, the process
deserves to be studied and monitored.

Sea-level
rise

Europe may be less threatened by sea-level rise than
many developing country regions. However, coastal ecosystems do
appear to be threatened, especially enclosed seas such as the Baltic, the Mediterranean and the
Black Sea. These seas have only small and primarily east-west
orientated movement corridors, which may restrict
northward displacement of organisms in these areas.[16] Sea
level rise for the next century (2100) could be between 30 and
100 cm and temperature shifts of a mere 0.05-0.1°C in the deep
sea are sufficient to induce significant changes in species
richness and functional diversity.[17]

Pollution

Pollution in this region has been extremely high in recent
years. The United Nations
Environment Programme has estimated that 650 million tons of sewage, 129,000 tons of mineral oil, 60,000
tons of mercury, 3,800 tons of lead and 36,000 tons of phosphates
are dumped into the Mediterranean each year.[18] The
Barcelona Convention aims to
'reduce pollution in the Mediterranean Sea and protect and improve
the marine environment in the area, thereby contributing to its
sustainable development.'[19]

The Mediterranean is also plagued by marine debris. A 1994 study of the seabed using trawl nets around
the coasts of Spain, France and Italy reported a particularly high
mean concentration of debris; an average of 1,935 items per square
kilometre. Plastic debris accounted for 76%, of which 94% was
plastic bags.[21]

Shipping

Some of the world’s busiest shipping routes are in the Mediterranean
Sea. It is estimated that approximately 220,000 vessels of more
than 100 tonnes cross the Mediterranean Sea each year – about one
third of the world’s total merchant shipping. These ships often
carry hazardous cargo, which if lost would result in severe damage
to the marine environment.

The discharge of chemical tank washings and oily wastes also
represent a significant source of marine pollution. The
Mediterranean Sea constitutes 0.7 percent of the global water
surface and yet receives seventeen percent of global marine oil
pollution. It is estimated that every year between 100,000 and
150,000 tonnes of crude oil are deliberately released into the sea
from shipping activities.

Approximately 370 million tonnes of oil are transported annually
in the Mediterranean Sea (more than 20 percent of the world total),
with around 250 to 300 oil tankers crossing the Sea every day.
Accidental oil spills happen frequently with an average of 10
spills per year. A major oil spill could occur at any time in any
part of the Mediterranean.[17]

Tourism

With a unique combination of pleasant climate, beautiful
coastline, rich history and diverse culture the Mediterranean
region is the most popular tourist destination in the world -
attracting approximately one third of the world’s international
tourists.

Tourism is one of the most important sources of income for many
Mediterranean countries. It also supports small communities in
coastal areas and islands by providing alternative sources of
income far from urban centres. However, tourism has also played
major role in the degradation of the coastal and marine
environment. Rapid development has been encouraged by Mediterranean
governments to support the large numbers of tourists visiting the
region each year. But this has caused serious disturbance to marine
habitats such as erosion and pollution in many places along the
Mediterranean coasts.

Tourism often concentrates in areas of high natural wealth,
causing a serious threat to the habitats of endangered
Mediterranean species such as sea turtles and monk seals. It is
ironic that tourism in this region is destroying the foundations of
its own existence. And it is inevitable that the tourists will
leave the Mediterranean as it becomes more depleted of its natural
beauty.[17]

Overfishing

Fish stock levels in the Mediterranean Sea are alarmingly low.
The European Environment Agency says that over 65 percent of all
fish stocks in the region are outside safe biological limits and
the United Nations Food and Agriculture Organisation, that some of
the most important fisheries – such as albacore and bluefin tuna, hake, marlin, swordfish, red mullet and sea bream - are
threatened.

There are clear indications that catch size and quality have
declined, often dramatically, and in many areas larger and
longer-lived species have disappeared entirely from commercial
catches.

Large open water fish like tuna have been a shared fisheries
resource for thousands of years but the stocks are now dangerously
low. In 1999 Greenpeace published a report revealing that
the amount of bluefin tuna in the Mediterranean had decreased by
over 80 percent in the previous 20 years and government scientists
warn that without immediate action the stock will collapse.

Aquaculture

Aquaculture is
expanding rapidly - often without proper environmental assessment –
and currently accounts for 30% of the fish protein consumed
worldwide. The industry claims that farmed seafood lessens the
pressure on wild fish stocks, yet many of the farmed species are
carnivorous, consuming up to five times their weight in wild
fish.

Mediterranean coastal areas are already over exposed to human
influence, with pristine areas becoming ever scarcer. The
aquaculture sector adds to this pressure, requiring areas of high
water quality to set up farms. The installation of fish farms close
to vulnerable and important habitats such as seagrass meadows is
particularly concerning.

Aquaculture production in the Mediterranean also threatens
biodiversity through the introduction of new species to the region,
the impact of the farms' organic and chemical effluents on the
surrounding environment and coastal habitat destruction.

From LoveToKnow 1911

MEDITERRANEAN SEA. The Mediterranean is all
that remains of a great ocean which at an early
geological epoch, before the formation of the Atlantic, encircled half the globe along a
line of latitude. This
ocean, already diminished in area, retreated after Oligocene
times from the Iranian plateau, Turkestan, Asia Minor and the region of the north-west
Alps. Next the plains of eastern
Europe were lost, then the
AraloCaspian region, southern Russia and finally the valley of the Danube. The " Mediterranean
region," as a geographical unit, includes all this area; the Black
Sea and the Sea of
Marmora are within its submerged portion, and the climate of
the whole is controlled by the oceanic influences of the
Mediterranean Sea. Professor Suess, to whom the above description
is due, finds that the Mediterranean forms no exception to the rule
in affording no evidence of elevation or depression within historic
times; but it is noteworthy that its present basin is remarkable in
Europe for its volcanic and seismic activity. Submarine earthquakes
are in some parts sufficiently frequent and violent as seriously to
interfere with the working of telegraph cables. Suess divides the
Mediterranean basin into four physical regions, which afford
probably the best means of description: (I) The western
Mediterranean, from Gibraltar to Malta and Sicily, enclosed by the Apennines, the mountains of northern Africa, and of southern and
south-eastern Spain
(Cordillere betique). (2) The Adriatic, occupying the
space between the Apennines and the Dinaric group (Suess compares
the Adriatic to the valley of the Brahmaputra). (3) A part surrounded by the
fragments of the Dinaro-Taurus
arch, especially by Crete and Cyprus. This includes the Aegean
and the Black Sea, and its margin skirts the south coast of Asia
Minor. These three parts belong strictly to Eurasia. (4) Part of
the coastal region of IndoAfrica, terraced downwards in successive
horizontal planes from the Shot, reaching the sea in the Little
Syrte, and continuing to the southern depressions of Syria. Malta and Gozo are the only islands of the Mediterranean
which can be associated with this section, and, per
contra,the
mountain chain of north-west Africa belongs to Eurasia. Murray
(1888) estimates the total area of the Mediterranean at 813,000 sq.
m. Karstens (1894) breaks it up into parts as follows: Western
Mediterranean 841,593 Sicilian-Ionian basin 767,658 Greece and Levant basin 769,652 Adriatic Sea 130,656 Total.. 2 ,5 0 9,559
„ A more recent calculation by Kriimmel gives the total area as
2,967,570 sq. km. or 1,145,830 sq. M. (See Ocean.) Murray estimates
the total surface of the Mediterranean drainage area, with which
must be included the Black Sea, at 2,934,500 sq. m., of which
1,420,800 are Eurasian and
1,513,800 are African. The principal rivers entering the
Mediterranean directly are the Nile from Africa, and the Po, Rhone and Ebro from Europe.

Depth.

Fathoms.

Area.

Sq. Miles.

Volume.

Cub. Miles.

0 100 .

. 201,300

80,950

100 500 .

. 251,650

220,850

500-1000 .

81,300

189,200

1000-2000 .

. 263,250

217,050

Over 2000 .

. 15,500

1,750

813,000

709,800

Volume. Mean Depth.

Cub. Km. Fathoms.

Western Mediterranean

.

1,356,512

881

Sicilian-Ionian basin .

.

, 4 ,549

885

Levant .

.

, ,599

793

Adriatic Sea .

31,844

133

The physical divisions of the Mediterranean given above hold
good in describing the form of the sea-bed. The western Mediterranean is cut off by a bank crossing the narrow strait
between Sicily and Cape Bon, usually known as the Adventure Bank, on which
the depth is nowhere 200 fathoms. The mean depth of the western
basin is estimated at 881 fathoms, and the deepest sounding recorded is 2040
fathoms. In the eastern Mediterranean the mean depth is nearly the
same as in the western basin. The Sicilian-Ionian basin has a mean
depth of 885 fathoms, and the Levant basin, 793 fathoms. Deep water
is found close up to the coast of Sicily, Greece, Crete and the
edge of the African plateau. The steepest slope observed occurs off
the island of Sapienza, near Navarino, where 1720 fathoms has been
obtained only 10 miles from land. In 1897 the ship " Washington " obtained
depths of 2220 fathoms in the middle of the eastern Mediterranean;
and the Austrian expeditions in the " Pola " discovered in the " Pola Deep " (35° 44'
N., 21 45' E.), south-west of Cape Matapan, a maximum depth of 2046
fathoms. Between these two deep areas a ridge runs in a north-westerly direction 550
fathoms from the surface - possibly a projection from the African plateau. Another
bank i ioo fathoms from the surface runs south from the east end of
Crete, separating the Pola Deep from the depths of the Levant
basin, in which a depth of 1960 fathoms was recorded near Makri on
the coast of Asia Minor. The later expedition of the " Pola "
discovered the " Rhodes Deep "
(36° 5' N., 28° 36' E.), with a maximum depth of 2110
fathoms: this deep is closed to the south-east by a ridge running
south-east, over which the depth is 1050 fathoms. Off the coast of
Syria the " Pola "obtained four soundings of more than 1100
fathoms, and between Cyprus and the coast of Asia Minor only two
over 550 fathoms. Murray gives the following figures for the areas
and volumes of the Mediterranean at different depths: which gives a
mean depth over all of 768 fathoms. The following table is due to
Karstens: Kriimmel gives the total volume of the basin as 4,249,020
cubic kilometres or 1,019,400 cubic statute miles, and the mean
depth as 782 fathoms. (See Ocean.) Meteorology. - As already stated, the
" Mediterranean region " forms a distinct climatic unit, chiefly
due to the form and position of the Mediterranean Sea. The
prevailing winds in this region, which the sea traverses
longitudinally, are westerly, but the sea itself causes the
formation of bands of low barometric pressure during the winter
season, within which cyclonic disturbances frequently develop,
while in summer the region comes under the influence of the polar
margin of the tropical high pressure belt. Hence the Mediterranean region is
characteristically one of winter rains, the distinctive feature
becoming less sharply defined from south to north, and the amount
of total annual fall increasing in the same direction. The climate
becomes more continental in type from west to east, but there are
great local irregularities - the elevated plateaus of Algeria and Spain cause a rise
of pressure in winter and delay the rainy seasons: the rains set in
earlier in the west than in the east, and the total fall is
greater. Temperature varies greatly, the annual mean varying from
56° F. to 77° F. In the west the Atlantic influence limits the mean
annual range to about 10°-12° F., but in the east this increases to
36° and even 40°. Autumn is warmer than spring, especially in the
coastal regions, and this is exaggerated in the eastern region by
local land winds, which replace the cool sea-breezes of summer:
overcoats are ordinarily worn in Spain and Italy till July, and are then put aside till
October. Local winds form an important feature in nearly all the
coast climates of the Mediterranean, especially in winter, where
they are primarily caused by the rapid change of temperature from
the sea to the snow-clad
hinterlands. Cold dry winds, often of great violence, occur in the
Rhone valley (the Mistral),
in Istria, and Dalmatia (the Bora), and in the western Caucasus. In summer a north-west " trade "
wind, the Maestro, occurs in
the Adriatic. The Sirocco is
a cyclonic wind characteristic of the winter rainy season; in the
Adriatic it is usually accompanied by cloud and moisture, often by rain. In Sicily and southern Italy the Sirocco
occurs at all seasons; it is a dry, dusty wind from south-east or
south-west. The dust is chiefly of
local origin, but partly comes from the Sahara. Similar winds are met with in Spain (the
Leveche), but they reach
their greatest development in the Simooms of Algeria and Syria, and
the Khamsin of Egypt.

Temperature

The mean surface temperature of the waters of the Mediterranean
falls from south-east, where it is over 11111123° F., to
north-west, the average at the coast of the Gulf of Lyons being 60°. The isothermal of
65° runs from Gibraltar to the north of Sardinia, and thence by the Strait of Messina to the Gulf of Corinth. A similar distribution
is found loo fathoms from the surface, temperature falling from 60°
in the Levant to 55° east of Gibraltar. At 200 fathoms temperature
falls in the same way from 58° to 55°, but below 250 fathoms
temperatures are practically uniform to the bottom, 55 5° in the
western basin and 56 5° in the eastern. The bottom temperature
observed in the Pola Deep was 56.3°.

Salinity

In the extreme west the salinity of the surface water is about
36 3 per mille, and it increases eastwards to 37 6 east of Sardinia
and 39 0 and upwards in the Levant. Observations of salinity in the
depths of the western Mediterranean are very deficient, but the
average is probably between 38 o and 38 5. In the eastern basin the
" Pola " expedition observed salinities of 38 7 to 39 o to the east
of a line joining Cape Matapan with Alexandria, and 38 2 to 38 7 to the
west of it. The salter waters apparently tend to make their way
westwards close to the African coast, and at the bottom the highest
salinities have been observed south of Crete. Evnitzki states that
the saltest water of the whole basin occurs in the Aegean Sea.

Circulation

There is little definite circulation of water within the
Mediterranean itself. In the straits joining it with the Atlantic
and the Black Sea the fresher surface waters of these seas flow
inwards to assist in making good the loss by evaporation at the
surface of the Mediterranean, and in both cases dense water makes
its way outwards along the bottom of the channels, the outflowing
currents being less in volume and delivery than the inflowing.
Elsewhere local surface currents are developed, either drifts due
to the direct action of the winds, or streams produced by wind
action heaping water up against the land; but these nowhere rise to
the dignity of a distinct current system, although they are often
sufficient to obliterate the feeble tidal action characteristic of
the Mediterranean. Dr Natterer, the chemist of the " Pola "
expeditions, has expressed the opinion that the poverty of the
pelagic fauna is solely due to
the want of circulation in the depths.

sq. km. „ Deposits. - A great part of the bottom of the
Mediterranean is covered with blue muds, frequently with a yellow
upper layer containing a considerable proportion of carbonate of lime, chiefly shells of pelagic Foraminifera. In many
parts, particularly in the eastern basin, a calcareous or siliceous
crust, from half an inch to three
inches in thickness, is met with; and Natterer suggested that the
formation of this crust may be due to the production of carbonate
of ammonium where deposits containing organic matter are undergoing
oxidation, and the consequent precipitation of carbonate of lime
and other substances from the waters nearer the surface. This view,
however, has not met with general acceptance. (H. N. D.)

From BibleWiki

The Mediterranean Sea is connected to the Atlantic Ocean by a narrow passage called the Strait of Gibraltar. It is almost completely surrounded by land, on the north by Europe, on the south by North Africa, and on the east by the Middle East. It covers around 2.5 million km² (965 000 mi²). To the east it connects to the Sea of Marmara and the Black Sea, by the Dardanelles and the Bosporus respectively. The Sea of Marmara is often considered a part of the Mediterranean Sea, whereas the Black Sea is generally not. The 163 km (101 mi) long man-made Suez Canal in the southeast connects the Mediterranean Sea to the Red Sea.

History

As a sea around which some of the most ancient human civilizations were arranged, it has had a major influence on the history and ways of life of these cultures. It provided a way of trade, colonization and war, and was the basis of life (via fishing and the gathering of other seafood) for numerous communities throughout the ages. The combination of similarly shared climate, geology and access to a common sea has led to numerous historical and cultural connections between the ancient and modern societies around the Mediterranean.

Oceanography

Being nearly landlocked affects the Mediterranean Sea's properties. Tides are limited by the narrow connection with the Atlantic Ocean. The water is saltier, partly because of evaporation. The Mediterranean has a deep blue color.

Evaporation greatly exceeds precipitation and river runoff in the Mediterranean, a fact that is central to the water circulation within the basin.[1]p202 Evaporation is especially high in its eastern half, causing the water level to decrease and salinity to increase eastward.[1]p206 This pressure gradient pushes relatively cool, low-salinity water from the Atlantic across the basin; it warms and becomes saltier as it travels east, then sinks in the region of the Levant and circulates westward, to spill over the Strait of Gibraltar.[1]p206/7 Thus, seawater flow is eastward in the Strait's surface waters, and westward below; once in the Atlantic, this chemically distinct "Mediterranean Intermediate Water" can persist thousands of kilometers away from its source.[1]p207